Surface and interface characterization of chlorinated polyolefin coated thermoplastic polyolefin

Laser scanning confocal fluorescence microscopy measurements were performed on thermoplastic polyolefin (TPO) substrates that were coated with chlorinated polyolefin (CPO). The TPO investigated was a blend of high modulus polypropylene with an ethylene-butene copolymer (EBR9) containing 9 wt% butene. The CPO was a maleated chlorinated polypropylene containing 20 wt% Cl. The purpose of these experiments was to obtain detailed mechanistic information about the CPO-TPO interaction. To achieve acceptable contrast in these measurements, a fluorescent dye was covalently attached to a small portion or the CPO. Solvent wiping of the TPO substrates with isopropyl alcohol followed by xylenes prior to coating with CPO increased the mean roughness of the TPO surface by more than 100 nm; but it had a much larger effect on the roughness of the (several micrometers) CPO-TPO interface after coating. The EBR component of the TPO was shown to be exclusively responsible for the roughness increase. We also found evidence of a diffuse interface between the CPO and ERB components that was localized to sites in which the EBR was present at the TPO surface.